Magnetic recording media are widely used in audio tapes, video tapes, computer tapes, disks, and the like. Magnetic recording media may use thin, metal layers as the recording layers, or many comprise particulate magnetic compounds as the recording layer. The latter type of magnetic recording media employs particulate material such as ferromagnetic iron oxides, chromium oxides, ferromagnetic alloy powders, and the like, dispersed in binders and coated on a substrate.
In general terms, magnetic recording media generally comprise a magnetic layer coated onto at least one side of a non-magnetic substrate (e.g., a film for magnetic recording tape applications). In certain designs, the magnetic coating is formed as a single layer directly onto the non-magnetic substrate. In an alternative approach, a dual-layer construction is employed, including a lower support layer on the substrate and a thin magnetic recording layer on the lower support layer. The two layers may be formed simultaneously or sequentially. With this type of construction, the lower support layer is generally thicker than the magnetic layer.
The support layer is typically non-magnetic and generally comprised of a non-magnetic powder dispersed in a binder. Conversely, the magnetic recording layer comprises one or more magnetic metal particle powders or pigments dispersed in a binder system. With this in mind, the magnetic recording layer defines a recording surface and is configured to record and store information.
Magnetic tapes may also have a backside coating applied to the opposing side of the non-magnetic substrate in order to improve the durability, electro-conductivity, and tracking characteristics of the media. The backside coating is typically non-magnetic and generally comprised of non-magnetic powders dispersed in a binder system and typically combined with suitable solvents to create a homogenous mixture. The dispersion is then coated onto the substrate, dried, calendered if desired, and subsequently cured.
Magnetic recording tapes continue to evolve as density and capacity demands increase. In order to increase the density of such tapes, tape manufacturers typically strive to provide a magnetic recording tape with as smooth a recording surface as possible. To increase the smoothness of a surface (i.e., to decrease the roughness characteristic), magnetic recording tapes are calendered by steel and/or compliant rollers to compress the components of the magnetic recording tape. Conventional calendering includes heating the rollers to high temperatures (e.g., temperatures greater than 160° F. (71.1° C.)) and compressing the magnetic recording tape between adjacent rollers with pressures of greater than 2500 lbs/in (437.7 N/mm) of tape width. Typically, such calendering results in a magnetic recording tape with a dense magnetic recording layer enabling increased recording density and decreased error rates relative to non-calendered media. However, such calendering can serve to effectively seal off the recording surface from porosity extending throughout the remainder of a magnetic side of the magnetic recording tape which in turn inhibits the migration of lubricant to the surface of the magnetic recording layer thereby limiting durability.
Although the magnetic recording tapes described above are configured with a high recording density, it is desired to increase the durability and life span of high recording density magnetic recording tapes.